Define the events A and B for the die-tossing experiment:

A: Observe an odd number B: Observe a number less than 4 Since event A occurs if the upper face is 1, 3, or 5, it is a collection of three simple events and we write A = {E, E., E,}. Similarly, the event B occurs if the upper face is 1, 2, or 3 and is defined as a collection of three simple events: B = {E,, E, E,}.